JP2016150561A - Fiber-reinforced composite body and method for producing fiber-reinforced composite body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced composite body excellent in lightweight properties and strength; and a method for producing the same.SOLUTION: A fiber-reinforced composite body has an intermediate layer portion 13 which is harder than a resin foam that constitutes a core material portion 11 inside of a surface layer portion 12 formed of a fiber-reinforced resin material. The intermediate layer portion 13 is a low foamed portion having a lower foaming magnification ratio than that of an extruded and foamed sheet 11 or a non-foamed portion. The resin sheet 13 and the extruded and foamed sheet are laminated and integrated with each other by any one of a heat lamination method, an extrusion lamination method and a coextrusion method. The intermediate layer portion 13 is a non-foamed resin layer laminated on the surface of the resin foam which constitutes the core material portion 11, and is a non-foamed resin layer which includes any one of an epoxy-based resin, a polyester-based resin and an acrylic resin and has an average thickness of 0.01-2 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fiber reinforced composite and a method for producing the fiber reinforced composite.

In recent years, the resin foam molded body is covered with a sheet-like fiber reinforced resin material called FRP, etc., and the FRP exhibits excellent strength in the surface layer portion and the core material portion is made into a resin foam molded body, thereby exhibiting light weight. Fiber reinforced composites are used in various applications (for example, see Patent Document 1 below).
Since this type of fiber reinforced composite is lightweight and has high mechanical strength, demand is expanding in the automotive field, the marine field, the aircraft field, and the like.
Among the transportation equipment such as automobiles, ships, and airplanes, particularly in the automobile field, it is strongly required that the structural members are lightweight and have high strength.

JP 2013-188953 A

In the fiber reinforced composite as described above, the gain in terms of lightness increases as the expansion ratio of the resin foam constituting the core material portion is improved.
In addition, since glass fibers and carbon fibers that are widely used as reinforcing fibers in fiber reinforced resin materials have a higher specific gravity than general resins, the fiber reinforced composite is formed by the fiber reinforced resin material. The gain in terms of lightness increases as the thickness of the part and the fiber density are reduced.
On the other hand, if the resin foam that supports the surface layer part from the back side is made highly foamed or the surface layer part is thinned, the surface layer part bends when a local force is applied from the outside in the thickness direction of the surface layer part. Is likely to occur, and in some cases, the surface layer may be cracked.

Therefore, conventionally, it is difficult for the fiber-reinforced composite to further improve the light weight while suppressing the strength reduction.
This invention is made | formed in view of such a condition, Comprising: It aims at providing the fiber reinforced composite_body | complex excellent in the lightness and intensity | strength, and its manufacturing method.

As a result of extensive studies by the inventor in order to solve the above problems, an intermediate layer portion is provided inside the surface layer portion, and the surface layer portion is thinned by making the intermediate layer portion harder than the core material portion. However, the present invention has been completed by finding out that bending and cracking can be hardly caused.
In this specification, “hard” means a high value of durometer hardness defined in JIS K6253-3 “vulcanized rubber and thermoplastic rubber—how to obtain hardness—part 3: durometer hardness”. This means that the durometer hardness (instantaneous value) measured at normal temperature (for example, 23 ° C.) is high.

  The present invention relating to a fiber-reinforced composite for solving the above problems has a composite structure comprising a core part and a surface layer part covering the core part, the core part being a resin foam, The surface layer portion is a fiber reinforced composite formed of a fiber reinforced resin material including fibers and a resin, and an intermediate layer portion in contact with the surface layer portion from the inside is further interposed between the surface layer portion and the core material portion. Provided, and the middle layer portion is harder than the core portion.

  In addition, the present invention according to a method for manufacturing a fiber-reinforced composite for solving the above problems has a composite structure including a core material part and a surface layer part covering the core material part, and the core material part is A method of manufacturing a fiber reinforced composite, which is a resin foam, and wherein the surface layer portion is formed of a fiber reinforced resin material including a fiber and a resin, the surface layer portion and the core material portion Further, an intermediate layer portion in contact with the surface layer portion from the inside is further provided, and the intermediate layer portion is formed to be harder than the core material portion.

The fiber reinforced composite of the present invention has the intermediate layer portion harder than the core portion provided on the inner side of the surface layer portion, so even when an external force is applied in the thickness direction of the surface layer portion, It can be suppressed by the middle layer.
Therefore, according to the present invention, the surface layer portion can be thinned and the fiber density of the surface layer portion can be reduced, and a fiber-reinforced composite excellent in lightness and strength and a method for producing the same can be provided.

The schematic sectional drawing which showed the cross-section of the fiber reinforced composite of one aspect.

In the following, an embodiment of the present invention will be described by taking as an example the case where the fiber-reinforced composite has a five-layer structure as shown in FIG.
As shown also in FIG. 1 which is a schematic cross-sectional view relating to the fiber-reinforced composite of the present embodiment, the fiber-reinforced composite 1 of the present invention has a plate shape, and five layers are laminated in the thickness direction. Has a structured.
The fiber reinforced composite 1 has a composite structure that includes a core part 11 at the center in the thickness direction and further includes a surface layer part 12 that covers the core part 11 from both the front and back sides.
Further, the fiber reinforced composite 1 of the present embodiment includes an intermediate layer portion 13 between the core material portion 11 and each surface layer portion 12.

  That is, the fiber reinforced composite 1 according to the present embodiment includes two surface layer portions 12 constituting both surfaces, two surface layer portions 12 in contact with the surface layer portion 12 from the inside, and the core material. Both surfaces of the portion 11 are in contact with the inside of each middle layer portion 12.

The core part 11 of the present embodiment is formed of a resin foam.
The said surface layer part 12 is formed with the fiber reinforced resin material containing a fiber and resin.
In the present embodiment, the first surface layer portion 12 covering the plate-like resin foam constituting the core portion 11 from the one surface side and the second surface layer portion 12 covering the other surface side are not necessarily the same. It is not necessary to form with the thing of a material, The kind of resin and fiber to contain, These compounding ratios, etc. may differ.
The middle layer portion 13 provided between the surface layer portion 12 and the core material portion 11 is harder than the core material portion 11.
The first middle layer portion 12 provided between the first surface layer portion 12 and the core material portion 11 and the second middle layer portion 12 provided between the second surface layer portion 12 and the core material portion 11. The two middle layer portions 12 may have the same thickness or material, or may be different.

As the resin foam constituting the core material portion 11, for example, one obtained by extrusion molding or one obtained by molding resin foam beads in a mold can be employed.
In addition, as the resin foam, a resin foam obtained by foaming a bulk polymerized resin molded body can be adopted.
That is, as the resin foam constituting the core part 11, for example, a polymerizable monomer, a foaming agent that generates a gas above the softening temperature of a polymer obtained by polymerizing the monomer, and a chain transfer agent A polymerizable solution containing an additive such as a reducing agent and a reducing polymerization initiator, and a polymer obtained by polymerizing the polymerizable solution is heated and foamed. Also good.

  The resin that is the main component of the resin foam is, for example, thermoplastic polyester resin such as polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyphenylene ether resin, polymethacrylimide resin, polyolefin resin, polystyrene resin, polyamide. Based resins and the like.

The thickness of the resin foam constituting the core member 11 is preferably approximately 1 to 10 mm, more preferably 1 to 5 mm, and particularly preferably 1 to 3 mm.
In addition, a resin foam having a high expansion ratio is advantageous to exhibit excellent lightness in the fiber reinforced composite, while an excessively high expansion ratio is sufficiently excellent in the fiber reinforced composite. There is a risk that it will be difficult to exert strength.
Therefore, the resin foam preferably has an apparent density of 0.05 to 1.2 g / cm ³ , and more preferably 0.08 to 0.9 g / cm ³ .
The apparent density of the resin foam can be determined according to JIS K7222: 1999 “Foamed plastics and rubbers—Measurement of apparent density”.

About the said surface layer part 12, carbon fiber, glass fiber, an aramid fiber, a boron fiber, a metal fiber etc. can be contained as said fiber, for example.
Among these fibers, the fiber contained in the surface layer portion 12 is preferably carbon fiber, glass fiber, or aramid fiber, and among these, carbon fiber having a good balance between lightness and strength is more preferable.
The fiber is a cloth in which continuous fibers are used for warp or weft, and these are woven by plain weave or twill weave, and a sheet body (Uni Directional material, hereinafter referred to as “UD material”) in which continuous fibers are aligned in one direction. Also, a mat formed by pressing short fibers into a sheet shape, or short fibers can be contained in the surface layer portion 12 in a dispersed state.

In particular, when the surface layer portion 12 is provided with excellent resistance to external force, the surface layer portion 12 preferably includes the fibers in a state of cloth or UD material.
Moreover, it is preferable that the surface layer portion 12 includes a plurality of cloths and UD materials, and is provided in a state where the cloth and UD materials are laminated in the thickness direction of the surface layer portion 12.
Density Incidentally, the even at relatively low density carbon fiber Among exemplary fibers, ^typically have a density of ^{1.6g / cm 3 ~1.8g / cm 3} , than general resin The value of is high.
Therefore, when the surface layer portion 12 is excessively multi-layered with cloth or UD material, it may be difficult to make the fiber-reinforced composite exhibit sufficient lightness.
Accordingly, the number of cross layers and UD materials stacked in the surface layer portion 12 is preferably 8 layers or less, and more preferably 4 layers or less.

The resin that forms the surface layer portion 12 together with the fibers may be a thermosetting resin or a thermoplastic resin.
Among these, the thermosetting resin is not particularly limited, and is an epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin, and maleimide resin. And a resin obtained by prepolymerizing cyanate ester resin.
Among these thermosetting resins, the resin to be contained in the surface layer portion 12 is excellent in heat resistance, elastic modulus and chemical resistance, and therefore may be either an epoxy resin or a vinyl ester resin. preferable.

The thermoplastic resin is not particularly limited, and examples thereof include polyolefin resins, polyester resins, thermoplastic epoxy resins, polyamide resins, thermoplastic polyurethane resins, sulfide resins, and acrylic resins.
Among these thermoplastic resins, the resin to be contained in the surface layer portion 12 is preferably a polyester resin or a thermoplastic epoxy resin because it is excellent in adhesion to fibers and strength.

When the surface layer portion 12 has an excessive resin content, the binding property between the reinforcing fibers and the adhesiveness with the middle layer portion 13 may be insufficient and the resin content is too large. It becomes difficult for the surface layer itself to exhibit excellent mechanical strength.
Therefore, the content of the resin in the surface layer portion 12 is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass.

The thickness of the surface layer portion 12 is preferably 0.02 to 2 mm, more preferably 0.05 to 1 mm, and the basis weight of the surface layer portion 12 is preferably 50 to 4000 g / m ² , and preferably 100 to 1000 g / m ^2. It is more preferable that

The middle layer portion 13 can be formed of an inorganic sheet such as a metal sheet or a ceramic sheet, but is preferably a resin layer in consideration of the lightweight property of the fiber-reinforced composite.
The middle layer portion 13 in the present embodiment is a low foamed resin layer or a non-foamed resin layer having a lower foaming ratio than the resin foam constituting the core material portion 11.
The resin forming the middle layer portion 13 is not only hard, but also has excellent adhesion to the resin foam constituting the core material portion 11 and the fiber reinforced resin material constituting the surface layer portion 12. It is preferable.
Examples of resins that are hard and exhibit excellent adhesion to many types of resins and that are preferable for forming the middle layer 13 include epoxy resins, polyester resins, and acrylic resins. It is done.

Since the middle layer portion 13 usually has a higher density than the resin foam constituting the core material portion 11, it is preferable that the thickness is thinner in view of the lightweight property of the fiber-reinforced composite.
On the other hand, in order to prevent the surface layer portion 12 from cracking when an external force is applied to the surface layer portion 12 and prevent the surface layer portion 12 from cracking, it is preferable that the middle layer portion 13 has a certain thickness or more.
Therefore, the middle layer portion 13 preferably has an average thickness of 0.01 mm to 2 mm, more preferably 0.02 mm to 1.0 mm, and more preferably 0.02 mm to 0.7 mm. It is particularly preferable to have the following average thickness:
The “average thickness” means a value obtained by calculating the volume of the middle layer portion 13 per unit area and dividing the volume by the unit area.
The middle layer portion 13 preferably has a higher hardness than the core material portion 11 and is preferably a non-foamed resin layer.

About the hardness of this intermediate | middle layer part 13 and the said core material part 11, it produced based on JISK6253-3 "vulcanized rubber and thermoplastic rubber-how to obtain | require hardness-3rd part: durometer hardness". It can be measured by a commercially available durometer hardness meter.
In addition, when the thickness of the middle layer part 13 or the core part 11 is too thin to collect a test piece defined in the same standard, a plurality of samples may be stacked to form a test piece. A thick sheet body having the same density as that of the middle layer section 13 and the core section 11 is separately prepared from the resin composition having the same composition as that of the core section 11 and the hardness measurement test piece is collected from this sheet body. It may be.
The hardness measurement of the middle layer portion 13 and the core material portion 11 may be performed in the standard state of JIS (23 ° C. ± 1 ° C., 50% ± 2% RH), and the hardness of each may be obtained by an instantaneous value. it can.
Moreover, if it is only confirmed that the middle layer part 13 is harder than the core part 11, the surface layer part 12 is removed from the fiber reinforced composite, and the durometer hardness is set with the middle layer part 13 exposed on the surface. Then, the durometer hardness is measured again in a state where the middle layer portion 13 is removed and the core material portion 11 is exposed, and the former measurement is performed in such a manner that the push needle of the durometer hardness meter collides with the middle layer portion 13. This can be confirmed by the fact that the value exceeds the latter measured value.

In addition, regarding the middle layer part 13, the core material part 11, and the surface layer part 12, the strength of the fiber reinforced composite can be improved by making the middle layer part 13 thicker than a certain thickness.
Moreover, when the thickness of the middle layer portion 13 becomes too thin, it becomes difficult to sufficiently exhibit the effect of suppressing the deformation of the surface layer portion 12 and the function of adhesiveness.
However, in the fiber reinforced composite, when the middle layer portion 13 has a thickness of a certain level or more, it is difficult to obtain a strength improvement effect commensurate with an increase in weight.
Therefore, from the viewpoint of making the fiber reinforced composite particularly excellent in lightness and strength, the middle layer portion 13, the core material portion 11, and the surface layer portion 12 have the thickness of the core material portion 11 as the middle layer portion 13 or The thickness of the surface layer portion 12 is preferably thicker, and the thickness of the surface layer portion 12 is preferably thicker than the thickness of the middle layer portion 13.
That is, the middle layer portion 13, the core material portion 11, and the surface layer portion 12 are preferably thicker in the order of [core material portion> surface layer portion> middle layer portion].
Moreover, in order to express sufficient strength in the surface layer portion and to make the strength of the entire fiber-reinforced composite sufficiently excellent, the hardness of the core portion (type D durometer hardness) is preferably 5 or more, 7 or more is more preferable, and 9 or more is particularly preferable.
On the other hand, the hardness of the middle layer portion is preferably 18 or more, more preferably 25 or more, and particularly preferably 35 or more.
The middle layer portion preferably has a hardness of 10 or more, more preferably 20 or more, higher than that of the core material portion.
That is, in order to prevent the occurrence of cracks in the surface layer portion 12 by suppressing the bending when an external force is applied to the surface layer portion 12, and to exhibit the effect that the fiber-reinforced composite exhibits high strength more reliably, the middle layer portion Preferably has the hardness as described above.

In order to make the thickness of the middle layer portion 13 of this embodiment uniform, it is preferable that the middle layer portion 13 be formed of a resin sheet or the like rather than a highly fluid material such as a liquid or a paste.
Moreover, in carrying out the lamination of the middle layer portion 13 and the core material portion 11 simply, the fiber reinforced composite 1 is such that the resin foam constituting the core material portion 11 is an extruded foam sheet, and It is preferable that the resin sheet forming the middle layer portion 13 and the extruded foam sheet are laminated and integrated by any one of a heat laminating method, an extrusion laminating method, and a coextrusion method.

In the thermal laminating method, for example, two non-foamed resin sheets for forming the middle layer portion 13 are prepared, and a laminate is formed by sandwiching the extruded foam sheet between these resin sheets. It can be carried out by a method in which the resin sheet and the extruded foam sheet are heat-sealed through the laminated body between a pair of heating rollers provided with a gap narrower than the natural thickness.
As for the extrusion laminating method, extrusion foaming is performed using an extruder equipped with a circular die or a flat die, and the extrusion using an extruder equipped with a flat die while continuously producing a strip-like extruded foam sheet. A method of simply laminating a resin sheet for forming the middle layer portion 13 on one side or both sides of the foamed sheet in a molten state, and further, forming the middle layer portion 13 having a thickness adjusted by passing between thickness correcting rollers after the lamination. It can be implemented by adding a process.
Furthermore, in the coextrusion method, two-layer coextrusion or three-layer coextrusion can be performed to form the middle layer portion 13 on one or both sides of the extruded foam sheet constituting the core material portion 11.

In addition, if necessary, after the resin foam forming the core part 11, the fiber reinforced resin material forming the surface layer part 12, and the resin sheet forming the middle layer part 13 are individually manufactured, the thermal laminating method described above is used. Such a method may be adopted to form a fiber reinforced composite.
That is, a non-foamed resin sheet is sandwiched between a fiber reinforced resin sheet obtained by impregnating a cloth or UD material with a resin and a resin foam sheet, and this is passed between a pair of heating rollers. The laminated body is pressurized in the thickness direction of the non-foamed resin sheet and the laminated body is heated so that the fiber-reinforced resin sheet, the non-foamed resin sheet, and the resin foam are integrated by heat fusion. A reinforced composite may be formed.
In the method for producing a fiber reinforced composite, a fiber reinforced composite can be obtained in a single step, the surface layer portion 12 is formed by the fiber reinforced resin sheet, and the middle layer portion 13 is formed by the non-foamed resin sheet. The core material portion 11 can be formed by the resin foam while being formed.
At this time, a fiber reinforced composite may be formed using a general hot press instead of the heating roller.
Furthermore, in the case of forming a fiber-reinforced composite by setting a molding die in a hot press machine, the core part 11 is not a plate-like resin foam but a resin foam having a three-dimensional structure. May be.

  When using a hot press machine, for example, the use of a non-foamed resin sheet is omitted, and once the surface layer part of the resin foam is selectively compressed with a hot press machine, the part is made higher than the center part of the resin foam. Densified to obtain a resin foam having a low-density part having a lower density than the high-density part inside the high-density part formed by the densification, and the core part 11 is formed by the low-density part. The middle layer portion 12 may be formed by the high density portion while being formed.

  In addition, as a method of forming the middle layer portion by omitting the use of the non-foamed resin sheet, for example, when producing the extruded foam sheet constituting the core material portion 11, the extruded foam sheet immediately after being extruded from the die is used. Strong cooling is applied to the surface of the extruded foamed sheet to selectively suppress foaming of the extruded foamed sheet so that the central portion in the thickness direction of the extruded foamed sheet is in the state of the resin foamed sheet, and the surface layer is in the state of the non-foamed resin sheet. And a method of using the surface layer portion for forming the middle layer portion.

For cooling the extruded foam sheet, it is preferable to use an air ring as a cooling means in order to cool the entire front and back surfaces of the extruded foam sheet substantially uniformly.
For example, when cooling is performed by blowing air at 10 to 20 ° C. from the air ring to the extruded foam sheet immediately after extrusion, the amount blown from the outlet to the surface of the extruded foam sheet is 0.005 per 1 m ² of the outer surface. It is preferable to be within the range of 0.6 Nm ³ / m ² .
The temperature and amount of air can be confirmed using a thermometer and anemometer at a position within 3 mm from the air outlet of the air ring 1.

According to such a method of strong cooling, for example, a large amount of hydrocarbon-based foaming agent (propane, butane, pentane, hexane, etc.) can remain in the extruded foam sheet during the extrusion foaming.
This remaining foaming agent exhibits excellent secondary foamability in the extruded foam sheet.
Therefore, the extruded foam sheet in which the foaming agent remains as described above is increased in thickness by the action of the foaming agent when heated to bond the fiber reinforced resin material, and the expansion force by the foaming agent is increased. It can be diverted to the bonding force with the fiber reinforced resin material.

From this, the extruded foam sheet before bonding the fiber reinforced resin material preferably contains 1% by mass to 10% by mass of a foaming agent such as butane, and more preferably contains 2% by mass to 5% by mass. preferable.
The foaming agent content of the extruded foam sheet can be determined as follows.

(Foaming agent content)
First, the mass W1 of the sample collected from the extruded foam sheet is measured.
Next, the mass W2 of the foaming agent contained in the extruded foam sheet is measured.
The mass (W2) of the foaming agent can be measured using a gas chromatograph, and specifically can be measured as follows.

  A sample of 10 to 30 mg is taken from the extruded foam sheet, placed in a 20 mL vial, precisely weighed, the vial is sealed and set in a gas chromatograph with an autosampler, and the vial is heated at 210 ° C. for 20 minutes. After that, the gas in the upper space of the vial is quantitatively analyzed by the MHE (Multiple Headspace Extraction) method, and the mass W2 of the foaming agent contained is measured.

The MHE method referred to here is a quantitative method that utilizes the attenuation of the peak area obtained by repeating the release of gas phase gas in gas-solid equilibrium.
[GC measurement conditions]
Measuring apparatus: Gas chromatograph Clarus500 (manufactured by Perkin-Elmer)
Column: DB-1 (1.0 μm × 0.25 mmφ × 60 m: manufactured by J & W)
Detector: FID
GC oven temperature rising condition: initial temperature 50 ° C. (6 minutes)
Temperature increase rate: 40 ° C / min (up to 250 ° C)
Final temperature: 250 ° C (1.5 minutes)
Carrier gas (He), inlet temperature: 230 ° C, detection temperature: 310 ° C
Range: 20
Vent gas 30 mL / min (He), additional gas 5 mL / min (He)
Gas pressure: Initial pressure 18 psi (10 minutes), Pressure increase rate: 0.5 psi / min (up to 24 psi)
[HS measurement conditions]
Measuring apparatus: HS autosampler TurboMatrix HS40 (manufactured by Perkin-Elmer)
Heating temperature: 210 ° C., heating time: 20 minutes, pressurized gas pressure: 25 psi, pressurized time: 1 minute,
Needle temperature: 210 ° C, transfer line temperature: 210 ° C, sample introduction time: 0.08 minutes [Calculation conditions]
Standard gas for calibration curve: Gas mixture (manufactured by GL Sciences Inc.)
Mixed gas content: i-butane about 1% by mass, n-butane about 1% by mass, balance nitrogen Calculation method: The amount of blowing agent in the sample is calculated by the MHE method. All results are in i-butane equivalent.

The foaming agent content in the extruded foam sheet can be calculated based on the following formula.

Foaming agent content (% by mass) in extruded foam sheet = 100 × W2 / W1

A known thermoforming method can be adopted as a method for producing a fiber reinforced composite by laminating a fiber reinforced resin material on such an extruded foam sheet.
Examples of the thermoforming include vacuum forming, pressure forming, and compression forming.
Examples of thermoforming methods that apply vacuum forming, pressure forming, and compression forming include straight forming, drape forming, plug assist forming, plug assist reverse draw forming, air slip forming, and snapback. Examples include molding methods, reverse draw molding methods, plug assist / air slip molding methods, match molding methods, press molding methods, SMC molding methods, and thermoforming methods that combine these molding methods. Since a fiber-reinforced composite having a good appearance can be obtained even if a resin material is used, a press molding method and a match molding method are preferable.

  Since the fiber reinforced composite obtained in this way is excellent in mechanical strength and lightness such as compressive strength and bending strength, it is in the field of transportation equipment such as automobiles, aircraft, railway vehicles or ships, home appliances field, information terminals. It can be used for a wide range of applications such as fields, components for wind power generation, industrial machinery, medical equipment, and furniture, especially automobile parts (ceiling panels, bonnets, undercovers, floor panels, door panels, etc.), home appliances It can be suitably used as a device part (such as a housing).

The shape of the fiber reinforced composite according to this embodiment is not particularly limited.
The fiber-reinforced composite according to the present embodiment can be in various forms required for its use.

  Although no further detailed description will be given here, the fiber-reinforced composite of the present invention is not limited to the above examples, and this is appropriately adopted for conventionally known technical matters regarding the fiber-reinforced composite. Is possible.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
Example 1
100 parts by mass of polyethylene terephthalate (PET, trade name “CH-611” manufactured by Toyobo Co., Ltd., glass transition temperature Tg: 79 ° C., melting point: 249 ° C., IV value: 1.0), 0.72 parts by mass of talc, and A polyester resin composition containing 0.2 parts by mass of pyromellitic anhydride was supplied to a single screw extruder having a diameter of 65 mm and an L / D ratio of 35, and melt kneaded at 290 ° C.

  Next, from the middle of the extruder, butane containing 35% by mass of isobutane and 65% by mass of normal butane is press-fitted into the extruder so as to be 1.5 parts by mass with respect to 100 parts by mass of polyethylene terephthalate. The resin was uniformly dispersed in the resin.

Thereafter, at the front end of the extruder, the polyester resin composition in a molten state is cooled to 220 ° C., and then extruded and foamed in a cylindrical shape from a circular die attached to the front end of the extruder to produce a cylindrical body. After gradually increasing the diameter of this cylindrical body at a speed that achieves a predetermined thickness and supplying it to a cooling mandrel (cooling mandrel temperature 15 ± 10 ° C.) to cool the surface, the other surface is also the same Then, it is cooled by an air ring (air temperature 15 ± 10 ° C., air volume 0.9 Nm ³ / min), and the cylindrical body is continuously cooled in and out in the direction of extrusion, and is cut and cut between the peripheral surfaces. A polyethylene terephthalate resin foam sheet was produced by unfolding.

On the other hand, as a fiber reinforced resin material, a face material in which a twill weave made of carbon fiber is impregnated with a resin (trade name “Pyrofil Prepreg TR3523-395GMP” manufactured by Mitsubishi Rayon Co., Ltd., basis weight: 200 g / m 2, thickness: 0.00. 23 mm) were prepared.
The face material had a planar square shape with a side of 250 mm.
Further, the face material contained 40% by mass of an uncured epoxy resin as a thermosetting resin.

Two face materials were overlapped so that the warp yarns were 90 ° in length direction to form a multilayer face material.
Further, an epoxy adhesive film (Sumitomo 3M “AF191”, thickness 0.06 mm) was interposed between the polyethylene terephthalate resin foam sheet and the multilayer surface material to produce a laminate.

  Subsequently, the laminate is disposed between male and female molds, and the male and female molds are clamped to press-mold, a polyethylene terephthalate resin foam sheet is formed into a flat plate shape, and a fiber reinforced resin material is bonded with epoxy. A fiber reinforced composite comprising a core part made of the polyethylene terephthalate foamed sheet, a middle part made of the epoxy-based adhesive film, and a surface layer part made of the multi-layered surface material. The body was made.

During press molding, the laminate was held at 145 ° C., and the epoxy resin contained in the fiber reinforced resin material was controlled to maintain fluidity without being cured.
At the time of press molding, the laminate was expanded in the thickness direction of the foamed sheet to form a raised portion, and the crystallinity of polyethylene terephthalate constituting the polyethylene terephthalate resin foamed sheet was increased.
In addition, the mold was capable of producing a fiber-reinforced composite capable of collecting ten strip samples (strip samples having a lateral dimension of 25 mm and a depth dimension of 130 mm).

  Next, the laminate is heated to 145 ° C. for 5 minutes, the uncured epoxy resin contained in the fiber reinforced resin material is cured, and the fibers of the fiber reinforced resin material are bonded and fixed with the cured epoxy resin. Then, the fiber reinforced resin material was laminated and integrated on both surfaces of the polyethylene terephthalate resin foamed sheet to produce a fiber reinforced composite.

Thereafter, the fiber reinforced composite was cooled to 30 ° C. or lower, and then the male and female molds were opened to take out the fiber reinforced composite to obtain a fiber reinforced composite.
In the obtained fiber reinforced composite, the surface layer portion in which the fibers are bound by the cured thermosetting resin and formed into a desired shape along the male and female molds is formed on the entire surface of the core portion through the middle layer portion. The layers were in close contact and integrated.
The polyethylene terephthalate resin foamed sheet was stored for 48 hours at 25 ± 5 ° C. after extrusion.

(Examples 2-10, Comparative Examples 1-2)
As shown in Table 1, fiber reinforced composites were obtained using the following non-foamed resin sheet as the forming material for the middle layer portion and the following resin foam as the forming material for the core material portion.
<Non-foamed resin sheet>
EP: Epoxy adhesive film (Newport 102U, Newport Adhesives and Composites, Inc.) laminated to each thickness Polyester: Polyethylene terephthalate (PET, trade name “CH-611” manufactured by Toyobo Co., Ltd.) And single layer extrusion (0.15 mm or less) or layer extrusion (coextrusion) Silicon: KE42T (one-component curable silicone, manufactured by Shin-Etsu Silicone)
<Resin foam>
Formac: 10 times foaming ratio, manufactured by Sekisui Plastics Co., Ltd., each slice of thickness of product name “Formac HR # 1000 Grade”

About the fiber reinforced composites of each Example and Comparative Example, using the strip sample (25 mm × 130 mm), the “maximum point load” is measured, and the “maximum point load” is divided by the mass of the sample to obtain “mass. "Efficiency" was sought.
(Measurement of bending strength)
The bending strength of the fiber reinforced composite was measured using a small tabletop testing machine (trade name “FGS-1000TV / 1000N + FGP-100” manufactured by Nidec Symposium) and software “FGS-TV Ver2” for a small tabletop testing machine. .
The jig used was “FGTT-531” manufactured by Nidec Sympos.
The strip-shaped sample is placed on a support base, the maximum point load is measured under the conditions of a load cell 1000N, a test speed of 5 mm / min, a support base end jig 5R, and an opening width of 100 mm. The value obtained by dividing by the mass was taken as mass efficiency.

(Measurement of hardness)
The hardness of the core material portion and the middle layer portion (non-foamed layer) was measured using a type D durometer hardness meter (GS-720N, manufactured by Techlock Co., Ltd.).
For the middle layer, it is difficult to measure the durometer hardness by itself. Therefore, the number of samples required for the total thickness to exceed 3 mm are collected, and this sample is laminated to form a laminate. A plate-shaped body having a thickness of 3 mm was produced, and the durometer hardness was measured on the plate-shaped body.

  From the above, it can be seen that according to the present invention, a fiber-reinforced composite excellent in lightness and strength can be obtained.

Claims (5)

It has a composite structure including a core material part and a surface layer part covering the core material part, the core material part is formed of a resin foam, and the surface layer part is formed of a fiber reinforced resin material including a fiber and a resin. A fiber reinforced composite comprising:
A fiber-reinforced composite, further comprising an intermediate layer portion in contact with the surface layer portion from the inside between the surface layer portion and the core material portion, wherein the intermediate layer portion is harder than the core material portion. The resin foam constituting the core part is an extruded foam sheet,
The middle layer is a low-foamed or non-foamed resin sheet having a lower foaming ratio than the extruded foam sheet,
The fiber reinforced composite according to claim 1, wherein the resin sheet and the extruded foam sheet are laminated and integrated by any one of a heat laminating method, an extrusion laminating method, and a coextrusion method.   The middle layer portion is a non-foamed resin layer laminated on the surface of the resin foam constituting the core material portion, and includes any one of an epoxy resin, a polyester resin, and an acrylic resin. The fiber-reinforced composite according to claim 1 or 2, wherein the non-foamed resin layer has an average thickness of 0.01 mm to 2 mm. It has a composite structure including a core material part and a surface layer part covering the core material part, the core material part is formed of a resin foam, and the surface layer part is formed of a fiber reinforced resin material including a fiber and a resin. A fiber reinforced composite manufacturing method for manufacturing a fiber reinforced composite comprising:
A method for producing a fiber-reinforced composite, further comprising an intermediate layer portion in contact with the surface layer portion from the inside between the surface layer portion and the core material portion, wherein the intermediate layer portion is formed to be harder than the core material portion.   A resin foam having a low-density portion having a lower density than the high-density portion inside a high-density portion formed by selectively compressing a surface layer portion of the resin foam to be highly densified. The method for producing a fiber-reinforced composite according to claim 4, wherein the core portion is formed by the low-density portion and the middle layer portion is formed by the high-density portion.

Images